I had a very odd occurrence the other day at my very first PRS match, lol! I've been reloading for years and never had a headspace issue until now! I had loaded for a custom built bolt rifle in 260rem for this match and I couldn't get the bolt to close on a fresh batch of rounds I had loaded the day before ( no, I didn't chamber check before leaving the house, I had an oof moment, lol) Needless to say I went home and pulled the rounds and checked their headspace with my Hornady comparator tools and it was on the money with my rounds that chambered just fine to the .001... So I bumped the shoulder back another .001 and the rounds chambered perfectly but now I have doubt in my measuring tools. So all that was to ask this, what headspace/datum line comparators do you like and feel are more accurate than the Hornady comparators? I've looked at the Whidden and Wilson tools and am leaning toward the Wilson micrometer comparator. What does the hide have to say?
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Headspace hiccup and more accurate comparator recommendations
- Thread starter david8989
- Start date
Innovative Technologies (Larry Willis). I use this comparator to check every case after sizing... It works well..... Can't speak for other comparators, however... Set it up high near eye level and very quick to check desired case size dimension....
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So Im not really sure what the issue is because youre complaining about them being too big but then you say
But then you bump them further and they still chmaber fine?
So I dont get it but the feeling I get is that because you didnt bump it back enough you think your tools are lying even though you did bum them back far enough?
And if they werent chambering but did after you pulled the bullet its not the cases headspace clearance thats the issue, its the bullet.
So suffice it to say, whatever message youre trying to convey is muddled and confusing.
So it seems that it working just fine.
But then you bump them further and they still chmaber fine?
So I dont get it but the feeling I get is that because you didnt bump it back enough you think your tools are lying even though you did bum them back far enough?
And if they werent chambering but did after you pulled the bullet its not the cases headspace clearance thats the issue, its the bullet.
So suffice it to say, whatever message youre trying to convey is muddled and confusing.
Your OP is a little confusing, but my first question is: did you check your neck OD in the loaded rounds that didn’t chamber? If you pulled the bullets and resized them your neck would now be smaller until you seat a bullet in it. You need to check that out and verify what you find before jumping off a cliff and blaming your equipment.
Your Hornady comparator is as accurate as the calipers thatthey are attached to. No more and no less. Are you using a quality set of calipers or Harbor Freight?
My point is that you are blaming the equipment when the problem is you or your process. That’s not an attack on you, as we have all made learning errors at the reloading bench, but the first answer is not to buy more equipment when you have a process issue.
Another place to look is at the end of the neck. Is it belled out or sharp to catch a tight necked chamber? What reamer was used for this custom rifle chamber?
I once had a new barrel chambered for my .260 that had a tight match chamber that meant the neck area was on the tight end of the spec. That is great for bench rest and accuracy, but sucks for field matches and PRS in my opinion. I had the smith open up the neck to middle of Saami spec and all has been good since then.
So first, understand the problem you had. It is likely not the comparator.
Your Hornady comparator is as accurate as the calipers thatthey are attached to. No more and no less. Are you using a quality set of calipers or Harbor Freight?
My point is that you are blaming the equipment when the problem is you or your process. That’s not an attack on you, as we have all made learning errors at the reloading bench, but the first answer is not to buy more equipment when you have a process issue.
Another place to look is at the end of the neck. Is it belled out or sharp to catch a tight necked chamber? What reamer was used for this custom rifle chamber?
I once had a new barrel chambered for my .260 that had a tight match chamber that meant the neck area was on the tight end of the spec. That is great for bench rest and accuracy, but sucks for field matches and PRS in my opinion. I had the smith open up the neck to middle of Saami spec and all has been good since then.
So first, understand the problem you had. It is likely not the comparator.
I have the same problem with one of my rifles. I think the culprit is the case wall/ shoulder junction. Your comparator is reading off the datum, but the junction is longer. When the case is chambered the junction hits first and that’s why you can’t close the bolt. So instead of bumping .002”, I bump .004” because .002” causes hard bolt close.
Sorry about that, lol. So basically I'm worried that my gorilla hands combined with my digital caliper and hornady headspace gauges are giving me false readings. Because I checked 5 rounds that would chamber and 5 that wouldn't and the headspace read the same on all the rounds. I wanted suggestions on a more accurate way to measure headspace that takes my hands out of the equation. Thanks for baring with me.
I measured everything on the rounds that chambered and the ones that didn't. Everything was the same. I have been using the same set of cabelas calipers for years so I really think the problem is me and my gorilla hands. I was looking for a more hands off way of measuring to take me out of the equation
Your issue isn’t with the comparator. It’s just a chunk of metal. How close are you working to zero headspace? In other words, are you trying to bump the shoulder the the absolute minimum, or are you just bumping .002-.003? Seems like you’re working too close to zero headspace regardless.
Your cabelas caliper, are these dial or digital? Ever cleaned or adjusted them. Do they graduate to .001”, or .0005”. Youre saying your hands are just more gorilla than they used to be?
I like and use a comparator, but if that tool went down, I still have the rifle’s chamber to use as a gauge which would get me to a proper die setting.
Your cabelas caliper, are these dial or digital? Ever cleaned or adjusted them. Do they graduate to .001”, or .0005”. Youre saying your hands are just more gorilla than they used to be?
I like and use a comparator, but if that tool went down, I still have the rifle’s chamber to use as a gauge which would get me to a proper die setting.
Try a Wilson case gauge. Foolproof. No moving parts. One of our local respected gunsmiths and long time competitive shooter used to say about Stony Point comparators - the best thing to do with one is to put half of the parts in one trash can and half of the parts in another and then pray no-one finds the parts and puts it back together and uses it.
All of the above is pertinent.
The way I read it, the OP is trying to work with 0.001” headspace. If that’s the case, the overall measurement system accuracy comes into play, including ambient temperature. If you measure a cartridge at 83F and use that dimension to set the headspace at 60F at 0.001”, you end up with a cartridge 0.0005” longer than desired at 83F. That’s a 50% error in your headspace. This is due to the thermal expansion of the cartridge.
Bottom line is trying to maintain 0.001” is hard to maintain. If the ammunition is critical, then the above recommendation of 0.002”-0.003” is should result in reliability.
As you discovered already - gettin' fancy in the reloading room results in crappy days in the field. Full length size with a quality die, bump the shoulder back 2-3 thou, keep an eye on your brass OAL for trimming purposes (indication of high pressure of length changes rapidly), and get on with the shooting. No-one ever gained any positions on the scoresheet because they didn't push their shoulder back.
Is there potential for the Hornady "datum" insert being aluminum and present .001" of wear after repeated use?
I've heard of it being possible. My biggest concern is that another knock against the hornady stuff is the metal is a bit soft and I'm wonder if I'm able to kinda mash it a bit with varying pressures from my meat claws and get different measurements?
This is one of the reasons once I get the exact amount of shoulder bump I need, I usually go .0005-.001 more. If any case has some wonky spring back or I made an error with calipers, it should still chamber. And the slightly more bump isn’t going to work the brass enough to matter.
With calipers (and micrometers) you have to be cognizant of using the same method each time.
I can take my SAC gauges, drop a case in, get a measurement, spin the case and let it settle, get a different measurement. I can put a little extra pressure on the calipers and get .0005-.001 smaller, and I can put a lot of pressure on them and get .001-.002 squeeze.
Key is when taking measurement for your chamber to do the same thing (I apply just enough pressure to square it up, give a couple twists to settle it all) and then do the exact same thing when measuring sized brass.
Also, a good trick is to do this while looking away from the reading, then looking after it’s done. This keeps us from knowing we want to hit say 1.345 and we see 1.346 and apply a little pressure to see it 1.345.
There no correlation in accuracy/ lack of accuracy between zero headspace and a little headspace. As you just learned, any accuracy claims are moot if you can’t actually shoot the gun. A dude with a rock in his hand was more prepared for that match than you were.So thats what I ended up doing to my rounds that wouldn't chamber and they work fine now. I guess I was mainly wanting something more accurate for future use
Easy turbo, lol. I brought extra rounds and finished pretty decently for my first competition. As stated, I've been loading for the better part of a decade and never had headspace issues. It sounds like I messed up and put to much pressure on the calipers to make it read what I wanted and that was my error. I appreciate your insight and this will definitely have me changing up my process ever so slightly in the future
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